As announced last week Microsoft today released 2 bulletins, one addressing Internet Explorer (MS09-034) and the other addressing the ATL component of Visual Studio (MS09-035). The release outside of their normal patch window means that exploits for this vulnerability have been spotted in the wild and IT administrators should treat the fixes as high priority.
The main attack vector that the current exploit is using is browsing with Internet Explorer. An end-user browsing the Internet with a vulnerable version of IE can get their system taken over simply by looking at a websites that have malicious tables or ATL objects. To increase their reach, attackers have been using web application vulnerabilities to put these type of exploits on common, non-malicious sites, that end-users would not suspect of. Once infected the attacker can add the system to their botnet or use it to attack other machines inside the network where the system is hosted. This second mode of use of an infected computer is increasingly common and can lead to indirect exploitation of systems within corporate networks that do not even have external connectivity or a browser installed.
Ryan Smith will present on the issue at BlackHat in Las Vegas tomorrow and has a small preview up on his site….